scripts: fetch_cipd: support tagged versions

It can be easier to write version info using git tags, so support it.
There aren't any packages that use : in their path name, so splitting
that out early shouldn't be a problem.

BUG=None
TEST=unittests pass

Change-Id: Ib0da414a7a268014f3fbdc5d706acac417209ea5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4178016
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Lizzy Presland <zland@google.com>
Commit-Queue: Lizzy Presland <zland@google.com>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/fetch_cipd_unittest.py b/scripts/fetch_cipd_unittest.py
index bba4804..a952965 100644
--- a/scripts/fetch_cipd_unittest.py
+++ b/scripts/fetch_cipd_unittest.py
@@ -26,3 +26,9 @@
         uri = "cipd://chromiumos/infra/tclint/linux-amd64"
         with self.assertRaises(ValueError):
             fetch_cipd.ParseCipdUri(uri)
+
+    def testParseCipdUriGitVersion(self):
+        uri = "cipd://chromiumos/infra/tclint/linux-amd64:git_version:1234"
+        path, version = fetch_cipd.ParseCipdUri(uri)
+        self.assertEqual("chromiumos/infra/tclint/linux-amd64", path)
+        self.assertEqual("git_version:1234", version)